How does increasing or decreasing the starting HP of a monster effect their CR?

Why the Way of the Four Elements require 1 more Ki than spell lvl but Way of Shadow is 1-for-1?

UA: Spell-less Ranger

Spell-less Ranger (or Strider) article is in Unearthed Arcana article, you can find  here: http://dnd.wizards.com/articles/features/modifying-classes

 

Can Rogues use Cunning Action as Bonus after a Readied Action?